Phase transition of individual anatase TiO2 microcrystals with large percentage of (001) facets: a Raman mapping and SEM study.

TiO2 has been extensively studied in many fields including photocatalysis, electrochemistry, optics, etc. Understanding the mechanism of the anatase-rutile phase transition (ART) process is critical for the design of TiO2-based high-activity photocatalysts and tuning its properties for other applications. In this work, the ART process using individual anatase micro-particles with a large percentage of (001) facets was monitored and studied. Phase concentration evolution obtained via Raman microscopy was correlated with the morphological evolution observed in scanning electron microscope (SEM) images. The ART of anatase microcrystals is dominated by surface nucleation and growth, but the ART processes of individual anatase particles are distinctive and depend on the various rutile nucleation sites. Two types of transformation pathways are observed. In one type of ART pathway, the rutile phase nucleated at a corner of an anatase microcrystal and grew in one direction along the edge of the crystal firstly followed by propagation over the rest of the microcrystal in the orthogonal direction on the surface and to the bulk of the crystal. The kinetics of the ART follows the first-order model with two distinct rate constants. The fast reaction rate is from the surface nucleation and growth, and the slow rate is from the bulk nucleation and growth. In the other type of ART pathway, multiple rutile nucleation sites formed simultaneously on different edges and corners of the microcrystal. The rutile phase spread over the whole crystal from these nucleation sites with a small contribution of bulk nucleation. Our study on the ART of individual micro-sized crystals bridges the material gap between bulk crystals and nano-sized TiO2 particles. The anatase/rutile co-existing particle will provide a perfect platform to study the synergistic effect between the anatase phase and the rutile phase in their catalytic performances.

Tip-Enhanced Raman Imaging of Single-Stranded DNA with Single Base Resolution.

Tip-enhanced Raman scattering (TERS) is a promising optical and analytical technique for chemical imaging and sensing at single molecule resolution. In particular, TERS signals generated by a gap-mode configuration where a silver tip is coupled with a gold substrate can resolve a single-stranded DNA (ssDNA) molecule with a spatial resolution below 1 nm. To demonstrate the proof of subnanometer resolution, we show direct nucleic acid sequencing using TERS of a phage ssDNA (M13mp18). M13mp18 provides a known sequence and, through our deposition strategy, can be stretched (uncoiled) and attached to the substrate by its phosphate groups, while exposing its nucleobases to the tip. After deposition, we scan the silver tip along the ssDNA and collect TERS signals with a step of 0.5 nm, comparable to the bond length between two adjacent DNA bases. By demonstrating the real-time profiling of a ssDNA configuration and furthermore, with unique TERS signals of monomeric units of other biopolymers, we anticipate that this technique can be extended to the high-resolution imaging of various nanostructures as well as the direct sequencing of other important biopolymers including RNA, polysaccharides, and polypeptides.

Seeding fiber amplifiers with piecewise parabolic phase modulation for high SBS thresholds and compact spectra.

We propose using piecewise parabolic phase modulation of the seed laser for suppressing stimulated Brillouin scattering (SBS) in a fiber amplifier. Simulations are run with a 9 m passive fiber. Compared with random phase modulation and 0-π pseudo-random phase modulation, the piecewise parabolic phase waveform yields a higher SBS threshold per unit bandwidth. If the bandwidth is defined as the range of frequencies containing 85% of the total power, the threshold for parabolic phase modulation is 1.4 times higher than the threshold for the five- or seven-bit pseudo-random modulation format. If the bandwidth is defined more tightly, e.g., the range of frequencies containing 95% of the total power, the threshold for parabolic phase modulation is three times higher. For both cases, achieving a bandwidth of 1.5 GHz requires a maximum phase shift of ~30 radians. All of the waveforms are compared on the basis of the bandwidth required of the phase moduator. The coherence functions are calculated in order to compare their suitability for coherent combining.

Polarization-filtering and polarization-maintaining low-loss negative curvature fibers.

We propose a polarization-filtering and polarization-maintaining negative curvature fiber in which two nested resonant tubes are added to a standard negative curvature fiber with one ring of tubes. The coupling between the glass modes in the nested resonant tubes and the fundamental core modes is used to increase the birefringence and differential loss for the fundamental core modes in the two polarizations. We show computationally that the birefringence and the loss ratio between the modes in the two polarizations can reach 10-5 and 850, respectively. Meanwhile, the low-loss mode has a loss that is lower than 0.02 dB/m. The relatively simple design of this polarization-maintaining negative curvature fiber will be useful in hollow-core fiber devices that are sensitive to polarization effects, such as fiber lasers, fiber interferometers, and fiber sensors.

Repeat Prostate Biopsy Practice Patterns in a Statewide Quality Improvement Collaborative.

PURPOSE: We examined rebiopsies in MUSIC (Michigan Urological Surgery Improvement Collaborative) to understand adherence to guidelines recommending repeat prostate biopsy in patients with multifocal high grade prostatic intraepithelial neoplasia or atypical small acinar proliferation. MATERIALS AND METHODS: We analyzed data on men undergoing repeat biopsy, practice patterns and cancer detection rates. Multivariate regression modeling was used to calculate the proportion of patients undergoing rebiopsy. We used claims data to validate the treatment classification in MUSIC. To understand reasons for not performing rebiopsy we reviewed records of a sample of patients with atypical small acinar proliferation. RESULTS: We identified 5,375 men with a negative biopsy, of whom 411 (7.6%) underwent repeat biopsy. In 718 men with high grade prostatic intraepithelial neoplasia, 350 with atypical small acinar proliferation and 587 with high grade prostatic intraepithelial neoplasia and atypical small acinar proliferation or atypical small acinar proliferation alone at initial biopsy the rebiopsy rate was 20.7%, 42.5% and 55.6%, respectively. The adjusted proportion of patients with rebiopsy in each practice ranged from 0% to 17.2% (p <0.001). The overall cancer detection rate at rebiopsy was 39.3%. It was highest after atypical small acinar proliferation (adjusted probability 0.39, 95% CI 0.30-0.48), and after high grade prostatic intraepithelial neoplasia and atypical small acinar proliferation (adjusted probability 0.50, 95% CI 0.35-0.65). The greatest Gleason 7 or greatest detection rate of 41.1% was found in patients with high grade prostatic intraepithelial neoplasia and atypical small acinar proliferation. Chart review revealed that 45.5% of patients with atypical small acinar proliferation underwent prostate specific antigen testing instead of rebiopsy while 36% failed to undergo rebiopsy despite a recommendation. CONCLUSIONS: Rebiopsy rates vary in Michigan practices with relatively low use in men with high grade prostatic intraepithelial neoplasia and atypical small acinar proliferation or atypical small acinar proliferation alone. Quality improvement strategies should target patients with atypical small acinar proliferation and high grade prostatic intraepithelial neoplasia as they have the highest likelihood of cancer detection.

Visual Outcomes after Vitrectomy for Terson Syndrome Secondary to Traumatic Brain Injury.

PURPOSE: To evaluate visual outcomes after vitrectomy for intraocular hemorrhages secondary to traumatic brain injury. DESIGN: Retrospective, observational case series. PARTICIPANTS: A total of 28 eyes in 20 patients undergoing vitrectomy for Terson syndrome secondary to traumatic brain injury between 1997 and 2015. METHODS: We reviewed the records of patients undergoing a standard 20-gauge or 23-gauge pars plana vitrectomy for intraocular hemorrhages secondary to traumatic brain injury, and the timing of vitrectomy in relation to the inciting intracranial event was recorded. MAIN OUTCOME MEASURES: The primary outcome measure was the change in the preoperative visual acuity score at postoperative month 1 and at the last noted clinic appointment. RESULTS: A total of 28 eyes in 20 patients (all male) underwent pars plana vitrectomy for intraocular hemorrhages secondary to traumatic brain injury. The mean preoperative baseline logarithm of the minimum angle of resolution (logMAR) (Snellen) best-corrected visual acuity (BCVA) was 1.81±0.56 (20/1290). At 1-month postoperative follow-up, the mean BCVA was 0.30±0.33 (20/40). At the date of the last follow-up, the mean BCVA was 0.15±0.24 (20/30) and the median BCVA was 0.00 (20/20). Although the difference between preoperative and postoperative BVCA was significantly different at 1 month and the final postoperative clinic visits (P < 0.001), there was not a correlation between preoperative visual acuity as a predictor of final postoperative visual acuity outcome (r=-0.32; P = 0.09; 95% confidence interval [CI] -0.62 - 0.06). At the date of the last follow-up, the differences in visual outcomes between the individuals undergoing vitrectomy within 3 months of the inciting event, 0.08±0.15 (20/25), were not significantly different than those undergoing surgical intervention after 3 months, 0.18±0.27 (20/30) (P = 0.28). Three cases among those undergoing vitrectomy after 3 months were complicated by retinal detachment, none of which resulted in a BCVA worse than when the patient originally presented preoperatively. CONCLUSIONS: In this retrospective series of patients without other ocular pathology, surgical intervention effectively provided rapid visual recovery in the majority of individuals with intraocular hemorrhages secondary to traumatic brain injury, irrespective of the timing of vitrectomy or of preoperative visual acuity.

Advancements of vitreoretinal surgical machines.

PURPOSE OF REVIEW: This article reviews current advancements in vitreoretinal surgical machines. RECENT FINDINGS: The most recent advancement in vitreoretinal surgical machines include 27-gauge vitrectomy probes, new cutter designs, higher cut rate, improved intraocular pressure control, new endoillumination technologies, and combined anterior/posterior segment capabilities. SUMMARY: With recent advancements in vitreoretinal surgical machines, surgical incisions have become less traumatic and fluidics control has led to a more controlled posterior segment vitrectomy.

Bending-induced mode non-degeneracy and coupling in chalcogenide negative curvature fibers.

We study bend loss in chalcogenide negative curvature fibers with different polarizations, different tube wall thicknesses, and different bend directions relative to the mode polarization. The coupling between the core mode and tube modes induces bend loss peaks in the two non-degenerate modes at the same bend radius. There is as much as a factor of 28 difference between the losses of the two polarization modes. The fiber with a larger tube wall thickness, corresponding to a smaller inner tube diameter, can sustain a smaller bend radius. The bend loss is sensitive to the bend direction when coupling occurs between the core mode and tube modes. A bend loss of 0.2 dB/m at a bend radius of 16 cm, corresponding to 0.2 dB/turn, can be achieved in a chalcogenide negative curvature fiber.

Higher-order mode suppression in chalcogenide negative curvature fibers.

We find conditions for suppression of higher-order core modes in chalcogenide negative curvature fibers with an air core. An avoided crossing between the higher-order core modes and the fundamental modes in the tubes surrounding the core can be used to resonantly couple these modes, so that the higher-order core modes become lossy. In the parameter range of the avoided crossing, the higher-order core modes become hybrid modes that reside partly in the core and partly in the tubes. The loss ratio of the higher-order core modes to the fundamental core mode can be more than 50, while the leakage loss of the fundamental core mode is under 0.4 dB/m. We show that this loss ratio is almost unchanged when the core diameter changes and so will remain large in the presence of fluctuations that are due to the fiber drawing process.

Highly efficient cascaded amplification using Pr(3+)-doped mid-infrared chalcogenide fiber amplifiers.

We computationally investigate cascaded amplification in a three-level mid-infrared (IR) Pr(3+)-doped chalcogenide fiber amplifier. The overlap of the cross-sections in the transitions (3)H(6)→(3)H(5) and (3)H(5)→(3)H(4) enable both transitions to simultaneously amplify a single wavelength in the range between 4.25 µm and 4.55 µm. High gain and low noise are achieved simultaneously if the signal is at 4.5 µm. We show that 45% of pump power that is injected at 2 µm can be shifted to 4.5 µm. The efficiency of using a mid-IR fiber amplifier is higher than what can be achieved by using mid-IR supercontinuum generation, which has been estimated at 25%. This mid-IR fiber amplifier can be used in conjunction with quantum cascade lasers to obtain a tunable, high-power mid-IR source.

An Escape Room to Teach First- and Second-Year Medical Students Nephrology.

An escape room is a team-based activity that requires players to solve a series of puzzles to complete a story and "break out" of a room. It has recently gained traction in medical education for its ability to interactively and effectively present learning objectives. This was a prospective educational study that describes the successful application of a nephrology themed escape room for first- and second-year medical students. Compared to pre-escape room participation, the 52 students demonstrated a statistically significant improvement in self-reported knowledge for renal physiology (p < 0.01), pharmacology (p < 0.01), pathology (p < 0.01), and relevant clinical practice guidelines (p < 0.01). A majority of the students also claimed that the escape room was "more effective" than traditional lectures (80.8%) and textbooks (73.1%) and "equally effective" as third-party board preparation resources (69.2%) and their institution's problem-based learning curriculum (51.9%). The escape room also facilitated a high-level peer-to-peer collaboration with 82.7% and 76.9% of students reporting that they worked with someone in their year and outside of their year for at least half of the game, respectively. Ninety-five percent of the first-years and 84.6% of the second-years believed that the escape room was effective at preparing them for their respective exams, and an overwhelming majority (90.4%) described the escape room as "very enjoyable." Overall, this nephrology themed escape room was an engaging and well received educational modality and may be an effective supplemental study resource for medical students. Further studies are needed to assess knowledge acquisition. Supplementary Information: The online version contains supplementary material available at 10.1007/s40670-023-01917-6.

A Canadian National Survey Study of Harassment in Surgery-Still a Long Way to Go.

OBJECTIVES: Previous literature has consistently documented harassment and discrimination in surgery. These experiences may contribute to the continuing gender inequity in surgical fields. The objective of our study was to survey Canadian surgeons and surgical trainees to gain a greater understanding of the experience of harassment across genders, career stage, and specialty. METHODS: A cross-sectional, online survey was distributed to Canadian residents, fellows, and practicing surgeons in general surgery, plastic surgery, and neurosurgery through their national society email lists and via social media posts. RESULTS: There were 194 included survey respondents (60 residents, 11 fellows, and 123 staff) from general surgery (44.8%), plastic surgery (42.7%), and neurosurgery (12.5%). 59.8% of women reported having experienced harassment compared to only 26.0% of men. Women were significantly more likely to be harassed by colleagues and patients/families compared to men. Residents (62.5%) were two times more likely to report being harassed compared to fellows/staff (38.3%). Residents were significantly more likely to be harassed by patients/families while fellows/staff were more likely to be harassed by colleagues. There were no significant differences in self-reported harassment across the three surgical specialties. There was no significant difference in rates of reported harassment between current residents (62.5%), and fellow/staff recollections of their experiences of harassment during residency (59.2%). CONCLUSIONS: The prevalence of gender-based discrimination remains high and harassment prevalence remains largely unchanged from when current staff were in residency. Our findings highlight a need to implement systemic changes to support the increasing number of women entering surgery, and to improve surgical culture to continue to attract the best and brightest to the field.

Synergistic Effect of Laser, Water Vapor, and Electron-Beam on the Degradation of Quasi-Two-Dimensional Ruddlesden-Popper Perovskite Flakes.

Understanding the effects of laser light, water vapor, and energetic electron irradiation on the intrinsic properties of perovskites is important in the development of perovskite-based solar cells. Various phase transition and degradation processes have been reported when these agents interact with perovskites separately. However, detailed studies of their synergistic effects are still missing. In this work, the synergistic effect of three factors (exposure to laser light, water vapor, and e-beam) on the optical and physical properties of two-dimensional (2D) Ruddlesden-Popper (RP) perovskite flakes [(BA)2(MA)2Pb3Br10] has been investigated in an environmental cell. When the perovskite flakes were subjected to moderate laser irradiation in a humid environment after prior e-beam irradiation, the photoluminescence (PL) peak centered at 480 nm vanished, while a new PL peak centered at 525 nm emerged, grew, and then quenched. This indicates the degradation process of the 2D RP perovskite was a phase transition to a three-dimensional (3D) perovskite [MAPbBr3] followed by the degradation of 3D perovskite. The spatial distribution of the 525 nm PL signal shows that this phase-transition process spreads across the flake to the area as far as ∼40 µm from the laser spot. Without humidity, the phase transition happened in the laser-irritated area but did not spread, which suggests that moisture enhanced the ion migration from the laser-scanned area to the rest of the flake and accelerated the phase transition in the nearby area. Experiments with no prior e-beam irradiation show that e-beam irradiation is the key to activating the 2D-3D phase transition. Therefore, when the three factors work synergistically, a conversion from the 2D RP perovskite into the 3D perovskite is not localized and propagates through the perovskite. These findings contribute to our understanding of the complex interactions between external stimuli and perovskite materials, thereby advancing the development of efficient and stable perovskite-based solar cells.

Optical properties of solid-core photonic crystal fibers filled with nonlinear absorbers.

A theoretical and experimental investigation of the transmission of solid-core photonic crystal fibers (PCFs) filled with nonlinear absorbers shows a sharp change in the threshold for optical limiting and in leakage loss as the refractive index of the material in the holes approaches that of the glass matrix. Theoretical calculations of the mode profiles and leakage loss of the PCF are in agreement with experimental results and indicate that the change in limiting response is due to the interaction of the evanescent field of the guided mode with the nonlinear absorbers in the holes.

Self-stabilized quantum optical Fredkin gate.

The quantum optical Fredkin gate is an indispensable resource for networkable quantum applications. Its performance in practical implementations, however, is limited fundamentally by the inherent quantum fluctuations of the pump waves. We demonstrate a method to overcome this drawback by exploiting stimulated Raman scattering in fiber-based implementations. Using a Sagnac fiber-loop switch as a specific example, we show that high switching contrast can be maintained even in the presence of significant pump fluctuations. This unique feature of self-stabilization, together with high-speed and low-loss performance of such devices, point to a viable technology for practical quantum communications.

Impact of caudal block on revision rates after hypospadias repair: Multi-institution review.

INTRODUCTION: There is controversy surrounding the association between caudal block and complication rates after hypospadias repair. Conflicting results have been reported mostly from single-center, low volume studies and those that did not include relevant variables. OBJECTIVES: We hypothesized that caudal block is not associated with increased rates of reoperation after primary repair and is associated with more complex hypospadias surgery. STUDY DESIGN: The Clinical Practice Solutions Center database was queried to identify patients who received a primary hypospadias repair between 2009 and 2010. Primary hypospadias repair was further categorized as meatal advancement and glanduloplasty, distal, one-stage proximal, or one-stage perineal repair. Anesthesia coding was evaluated to identify those who received a caudal block. Any revision surgery was captured between 2009 and 2019 and the types of revision surgeries were identified. Variables such as caudal block, age, insurance type, surgeon volume, and surgeon years in practice were analyzed with mixed effects multiple logistic regression models. RESULTS: The dataset query identified 3343 pediatric males who had primary hypospadias repair. The procedures were performed by 50 surgeons at 27 hospitals. Primary surgeries included meatal advancement and glanduloplasty (23%), distal (69%), proximal (6.9%), and perineal repairs (1%). Caudal block was administered to 42% of patients. Utilization of caudal block was not associated with type of primary surgery (p = 0.21). Adjusting for all other variables, increased patient age was associated with decreased usage of caudal block (p < 0.001). Analysis did not demonstrate a statistically significant association between utilization of caudal block with rates of revision surgery. CONCLUSIONS: This large, multi-institution study demonstrates that the use of caudal block was not associated with more complex hypospadias surgery nor statistically significantly associated with increased rates of revision surgery after primary hypospadias repair.

The discovery of the DNA methylation episignature for Duchenne muscular dystrophy.

Duchenne Muscular Dystrophy (DMD) is an X-linked recessive neuromuscular disorder characterized by progressive muscle weakness due to loss of function mutations in the dystrophin gene. Variation in clinical presentation, the rate of disease progression, and treatment responsiveness have been observed amongst DMD patients, suggesting that factors beyond the loss of dystrophin may contribute to DMD pathophysiology. Epigenetic mechanisms are becoming recognized as important factors implicated in the etiology and progression of various diseases. A growing number of genetic syndromes have been associated with unique genomic DNA methylation patterns (called "episignatures") that can be used for diagnostic testing and as disease biomarkers. To further investigate DMD pathophysiology, we assessed the genome-wide DNA methylation profiles of peripheral blood from 36 patients with DMD using the combination of Illumina Infinium Methylation EPIC bead chip array and EpiSign technology. We identified a unique episignature for DMD that whose specificity was confirmed in relation other neurodevelopmental disorders with known episignatures. By modeling the DMD episignature, we developed a new DMD episignature biomarker and provided novel insights into the molecular pathogenesis of this disorder, which have the potential to advance more effective, personalized approaches to DMD care.

Using uniaxial tensile testing to evaluate the biomechanical properties of bladder tissue after spinal cord injury in rat model.

To investigate the biomechanical properties of rat bladder tissue after spinal cord injury (SCI) using uniaxial tensile testing. Evidence suggests the bladder wall undergoes remodeling following SCI. There is limited data describing the biomechanical properties of bladder wall after SCI. This study describes the changes in elastic and viscoelastic mechanical properties of bladder tissue using a rat model after SCI. Seventeen adult rats received mid-thoracic SCI. Basso, Beattie, and Bresnahan (BBB) locomotor testing was performed on the rats 7-14 days after injury quantifying the degree of SCI. Bladder tissue samples were collected from controls and spinal injured rats at 2- and 9-weeks post-injury. Tissue samples underwent uniaxial stress relaxation to determine instantaneous and relaxation modulus as well as monotonic load-to failure to determine Young's modulus, yield stress and strain, and ultimate stress. SCI resulted in abnormal BBB locomotor scores. Nine weeks post-injury, instantaneous modulus decreased by 71.0% (p = 0.03) compared to controls. Yield strain showed no difference at 2 weeks post-injury but increased 78% (p = 0.003) in SCI rats at 9 weeks post-injury. Compared to controls, ultimate stress decreased 46.5% (p = 0.05) at 2 weeks post-injury in SCI rats but demonstrated no difference at 9 weeks post-injury. The biomechanical properties of rat bladder wall 2 weeks after SCI showed minimal difference compared to controls. By week 9, SCI bladders had a reduction in instantaneous modulus and increased yield strain. The findings indicate biomechanical differences can be identified between control and experimental groups at 2- and 9-week intervals using uniaxial testing.

Giant and uniform fluorescence enhancement over large areas using plasmonic nanodots in 3D resonant cavity nanoantenna by nanoimprinting.

Using a new nanoplasmonic architecture and an optimized spacer, we observed the following: (a) the average fluorescence of an infrared dye (indocyanine green) is enhanced by 2970 fold uniformly (variation < 11%) over a large sample area and over a wide range of dye concentrations (380 to 380,000 molecule µm(-2)), laser excitation powers and laser beam sizes; and (b) for a single molecule placed at a 'hot spot', the fluorescence enhancement is 4.5 × 10(6) fold. The giant and uniform enhancements (orders of magnitude higher than before), plus easy and inexpensive large area fabrication ( > 4″ wafers), should open up wide applications.

The Efficacy of an Immersive Virtual Reality Exergame Incorporating an Adaptive Cable Resistance System on Fitness and Cardiometabolic Measures: A 12-Week Randomized Controlled Trial.

Exergaming, combining elements of video game into the realm of exercise, has recently incorporated immersive virtual reality (IVR) with resistance training. Thirty-two participants (14 females, mean age = 24.3) were randomized to IVR or self-directed control group (SELF) and worked out thrice weekly for 12 weeks (for 36 sessions). The IVR group spent 14 fewer minutes per session (p < 0.001) while reporting the sessions "enjoyable'. Compared to SELF, the IVR group had significantly greater improvement in changes from baseline to post-training in upper-and-lower muscular strength (1-RM) and muscular endurance (85% 1-RM) (14.3 kg vs. 10.0 kg for 1-RM upper, 28.6 kg vs. 22.5 kg for 1-RM lower, 2.6 reps vs. 1.9 reps for 85% 1-RM of upper, 2.7 vs. 2.0 reps for 85% 1-RM of lower, all p < 0.001), peak leg power (1424 vs. 865 W, p < 0.001), body fat% (−3.7% vs. −1.9%, p < 0.001), heart rate variability (4.3 vs. 1.8 ms, p < 0.001), rVO2max (3.28 vs. 0.89 mL/min/kg, p < 0.001) with decreased systolic BP (−0.4 vs. −2.3 mmHg, p < 0.001), and level of perceived exertion during workouts (RPE 14 vs. 16, p < 0.001). With its high-paced and action-filled gaming coupled with superior fitness and cardiometabolic outcomes, this IVR exergaming platform should be considered as another exercise modality for performance and health-related training.